SRAM on the mystorm blackice

mystorm blackice has 0.5MByte SRAM on the back of the board

datasheet for SRAM

mystorm blackice schematic

From datasheet: ISSI IS62WV25616DALL and IS62/65WV25616DBLL are high-speed, low power, 4M bit SRAMs organized as 256K words by 16 bits.

verilog

• extremely simple test of the SRAM
• state machine for read and write
• everything done in 1 cycle as 1 cycle at 12MHz is slower than max read/write time of the SRAM.

sram.v

current status

• working at 12MHz system clock
• test reads then writes to first 2^16 words
• data written is the current address
• bits 14:11 of the data is shown on the boards's 4 leds
• boring test video

testbench

sram_tb.v

problems

2 pins on the data bus collide with pins of the PLLs. When the PLL is activated, those pins can no longer be inout, they must be either in or out. More details here